Grid electrodes for electron discharge devices



Oct. 20, 1959 c F. MILLER .ET AL GRID ELECTRODES FOR ELECTRON DISCHARGEDEVICES 2 Sheets-Sheet 1 Filed April 1, 1955 15 lam- X INVENTORS ErnestF. Smart WITNESSES Carl F. Mill er, and Gene R. Feoster.

f ATTORNEY Maya;

Oct. 20, 1959 c. F. MILLER ETAL 2,999,200

' GRID ELECTRODES FOR' ELECTRON DISCHARGE DEVICES Filed April 1, 1955 2Sheets-Sheet 2 Fig.6.

v eni (a United States Patent C M GRID ELECTRODES FOR ELECTRON DISCHARGEDEVICES Carl F. Miller, Bath, and Ernest F. Smart and Gene R. Feaster,Horseheads, N.Y., assignors to Westinghouse Electric Corporation, EastPittsburgh, Pa., a corporation of Pennsylvania Application April 1,1955, Serial No. 498,538 '1 Claim. (Cl. 140-715 This invention relatesto electron discharge devices and more particularly to improvements inor relating to the construction of grid electrodes for use in saidelectron discharge devices.

In general, the present invention involves placing a :number of gridframe members on a support member, winding wire material around thesupport member at .:any desired pitch, joining the wire material to thegrid I'frame members at the intersections of the wire material and thegrid frame members, and separating the com- ,pleted grids from eachother by cutting the wire material between adjacent grid frame members.

It is an object of this invention to provide a method of manufacturinggrid electrodes for electron discharge devices.

It is another object to provide a method for manufac turing gridelectrodes for electron discharge devices, which method is suitable foruse in the automatic production of electronic parts.

It is an additional object to provide an improved grid electrode sturdyenough to be used in automatic production methods of manufacture.

It is a different object to provide a method of manufaeturing gridelectrodes for electron discharge devices, which method results in alower percentage of rejected grids and, therefore, in higher efficiencyin the manufacture of grid electrodes.

It is still another object to provide an improved method of attachinglateral grid wires to grid frames.

These and other objects of the invention will be apparent from thefollowing description taken in accordance with the accompanying drawingswhich form a part of this application, and in which:

Figure l is a partial end view of the apparatus upon which the gridframe members are mounted during manufacture of the grid electrodes;

Fig. 2 is a top view of the apparatus of Fig. 1;

Fig. 3 is a view in elevation, partly in section, of a suitable methodof joining grid wires to grid frame members;

Fig. 4 is a perspective View of the apparatus used to separate thecompleted grid electrodes from each other;

Fig. 5 is a cross sectional view of a part of Fig. 4 "showing thecutting of the wires between the grid frame :members; and

Fig. 6 is an exploded perspective view of another form of the apparatusupon which the grid frame members are mounted during manufacture of thegrid electrodes.

In Fig. 1 there is shown a shaft member 11, which may be rotatable, ifdesired, around which a mandrel member 13 is positioned. A key member 15is used in positioning the mandrel member 13 on the shaft member 11.Grid frame members 17 are attached to the mandrel member 13. Suitablemethods of attaching the grid frames 17 to the mandrel member 13 includeproviding the shaft member 11 and the mandrel member 13 with Iainternalchannels by which the grid frames 17 may be held by.vacuum to themandrel member 13. Another method is to utilize magnetic attraction toattachthe grid frames 17 to the mandrel member 13. Also the edges of thegrid frames 17 can be held to the mandrel member 13 by a clip. Anothersuitable method is shown by Fig. 2. Wirematerial 19 is wound around themandrel member 13 in such a manner as to cross the grid frames 17 anumber of times. The spacing and the pitch.

of the wire 19 are guided by a guide member 21. After the windingoperation, if desired, the mandrel member 13 may be removed from theshaft member 11 and may with a source of compressed gas to eject a sprayof molten metal. The metal spray gun 25 is supplied with a rod 27 of asuitable metal to be used in joining the grid wires 23 to the grid frame17. In operation, the metal spray gun 25 creates a flame of intense heatin which the rod 27 is fused and is immediately subjected to a blast ofair or gas whereby the molten metal is projected as a spray 29 of fusedmetal.. The gas may be such as to prevent oxidation of the metal spray.In this way, a metal coating 31 is formed over the intersections of thelateral gridwires 23 and the grid frame members 17 so that thelateralgrid wires 23 are bonded to the grid frame member 17. Since it ispossible to spray a large variety of metals by the Schoop process, awide choice of metals are available for use in joining the grid wire 23to the grid frame members 17. Molybdenum has been found to be a suitablemetal for use ,in the Schoop process, as have the brazing solder powdersdiscussed below. Suitable masking to avoid metal deposition inundesirable locations may be used. Other methods which may be used tojoin the lateral grid wires 23 to the grid frame member 17 include coldwelding, welding, notching and peening, and brazing.

In Fig. 4 there is shown the shaft member 11, the mandrel member 13, thekey member 15, the grid frame member. 17 and the lateral cross wires 23.Cutting members 33 are mountedon a cutting member supportmember 35between rubber. pads 37.. .The cutting member support member 35is'gearedtothe shaft member 11 so that as the shaft member 11 is rotated,the cutting member support member 35 is rotated in such a manner as toposition a cutting member 33 between each grid frame member 17 so thatthe wire material between the grid frames 17 is severed, thus separatingthe completed grid electrodes 39 from each other.

A suitable grid electrode is shown in Fig. 4 including a grid framemember 17 having a U-shaped cross section, a flat middle portion 41 andat least one aperture 20 in the flat middle portion 41. Lateral gridwires 23 are positioned across the aperture 20 and joined to the gridframe member 17 by any of the methods discussed elsewhere in thisapplication. The grid electrode 39 has tapered leg members 45 at the endportions. It is apparent, however, that the present invention is notnecessarily limited to grid electrodes of the above configurations. Theedge portions 49 of the grid frame member 17 may be positioned at anydesired anglewith respect to the flat middle portion 41 of the gridframe member 17 including perpendicular and coplanar configurations.

In Fig. 5 there is shown the actual cutting operation in which thecutting member 33 is severing the wires 23 Patented Oct. 20, 1,959

whichgrid frames similar to the grid frame member 1.7.2

showninFig. 1 may bemounted. 'I 'he grid frame rnembers areheld inposition by collar members 55 and 57. The mandrel member 53 with thegrid frame members.

and collar membersSS and 57' attached is thenfitted to; the shaft member51 and locked into position by screwing end member 59 into the shaftmember 51. After the winding operation the mandrel member 53 with thecollar members 55 and 57 still attached may be removed from the shaftmember 5-1 and brazed if desired. After the brazing operation, collarmembers 55 and 57 are removed from themandrel member 53 before the gridsare separated as is shown in Fig. 4. The mandrel members may have asmooth surface as shown by mandrel member- 53 or a notched surface asshown by mandrel member 13 in Fig. 1.

Materials used for the grid frame members 17 and the lateral grid wires23 must be chosen carefully. It is very important that the coeflicientsof thermal expansion of the grid frame members 17, the lateral gridwires 23, and any brazing materials-used in joining the lateral gridwires 23 to the grid frame members 17, be closely matched. A firstcombination of suitable materials would include grid frames 17 made of.015 inch sheet Kovar with lateral wires made of gold plated molybdenumof .002 inch diameter. In addition, if brazing is the method used tojoin the lateral wires 23 to the grid frame members 17, a suitablesolder powder is composed of 15%,silver, 80% copper and 5% phosphorous,and is heated at 700 C. for three minutes. A second combination ofsuitable materials would include grid frames 17 made of .010 inch sheetsteel of the type known in the trade under the designation SAE 1010 andlateral wires made of .002 inch diameter stainless steel. Again, ifbrazing is used as the method for joining the lateral wires 23-to thegrid frames 17, the preferred solder powder may be either one composedof 15% silver, 80% copper and 5% phosphorous which is heated at 7 00 C.for three minutes or a powder composed of 60% silver, 30% copper andtin, which is heated at 750 C. for three minutes. In the brazing processmethanol binders are suitable. Another suitable binder is polymerizedmethyl methacrylate, known under the trade name Lucite.

This invention utilized a method suited for fully automatic gridmanufacture procedures with -a reduction of labor costs, improvedefiiciency and better control of tolerances. These grid electrodes maybe made with from 100 to 400 lateral wires 23 per inch. The number ofgrid frame members 17 mounted on the mandrel member 4 13 or 53 may varyin number but groups of 2, 10 and 20 grid electrodes have been made atone time by this method. The wire 19 must be attached to the first gridby known methods such as spot welding or by the use of pins.

The mandrel member 13 or 53 may be of any desired shape or configurationbut a cylindrical mandrel member is preferred. because, using thisshape, the circular winding speed is uniform which results in moreuniform tension of the lateral grid wires 23. After completing thewinding, the wire 19 is fastened to the last grid'frame member 17 in thesame manner as it was first attached. Also, more than one mandrel member13 may be supported on the same shaft member 11 allowing more grids tobe manufactured in one operation.

While the present invention has been shown in a few preferred formsonly, it will be obvious to those skilled in the art that it is not solimited but is susceptible of various changes and, modifications withoutdepartingfrom the spirit thereof.

We claim as our invention:

A method of fabricating a plurality of frame grid members characterizingand having a planar support member with an aperture therein and lateralwires overlying and extending beyond said aperture, said methodincluding the steps of providing a mandrel member, providing a pluralityof positioning means on the surface of said mandrel for individuallypositioning a plurality of support members therein, securing saidsupport members to the surface of said mandrel by magnetic attraction,winding wire material at equally spaced intervals across the aperturesin said frames thereby providing a suitable number of lateral wires foreach of said support members, spraying a molten metal onto said lateralwires and said support member to bond said lateral wires to said supportmember and separating the completed grid electrodes from each other andthe mandrel to provide a plurality of individual frame grid electrodemembers.

References Cited in the file of this patent UNITED STATES PATENTSBongers Dec. 13, 19

